<?php
header("Content-Type: text/html;charset=utf-8");
echo '<select name="servicio" id="servicio">';
$bd_host = "localhost"; 
$bd_usuario = "root"; 
$bd_password = ""; 
$bd_base = "centroservicios"; 
$con = mysql_connect($bd_host, $bd_usuario, $bd_password); 
mysql_select_db($bd_base, $con); 
mysql_query("SET NAMES 'utf8'");
$consulta = mysql_query("SELECT * FROM costos",$con);

while($fila = mysql_fetch_array($consulta)){	
		
		 if($fila['idlinea']==$_GET['c'])
			echo "<option value='".$fila['idcostos']."'>".$fila['nombreservicio']."-$".$fila['costo']."</option>";;
		
	}
mysql_close($con);
echo '</select>';
?>